One of the fundamental requirements for mobile backhaul networks connecting multiple users is reliability. In some networks, different types of material are used for wired links between different entities. Also some networks comprises radio base stations typically outdoor units, together with indoor units and radio heads. These different units may be connected by wire, e.g. fibre cables.
In order to assure reliability, there is a need for a link supervision solution to proactively and reactively monitor link status and quality.
In subcarrier multiplexed, SCM, transmission where several (for example) radio signals related to different operators and/or different radio technologies are provided on separate optical subcarriers, one of the data subcarriers or an idle (dedicated) subcarrier may be assigned to link monitoring purposes.
However, existing techniques for link monitoring based on reflectometry utilize a dedicated optical carrier which implies deployment of an extra laser dedicated only for monitoring purposes. This incurs extra cost for the operator.